Angular SSR with .NET 8 API hosted on IIS – site sometimes slow to load even with normal...

I’ve developed a website using Angular with SSR build for the frontend and .NET 8 Web API for the backend. Both applications are hosted on the same IIS server (Windows).

The site usually runs fine, but sometimes it takes noticeably longer to load in the browser.

Here’s what I’ve checked when the issue occurs:

CPU usage on the app server is around 20%

Memory usage is around 20%

Database server is normal, queries execute within acceptable time limits

Users are few (not high traffic at the time)

So backend and DB performance look fine, but the frontend still responds slowly.

My questions:

Could this be due to IIS hosting configuration for Angular SSR (e.g., warm-up, application pool recycle, preload, etc.)?

Are there any best practices for Angular SSR hosting on IIS to reduce first load time?

What else should I check (logs, IIS settings, network, caching, etc.) to identify why the frontend takes time to load intermittently?

Environment:

Angular SSR build (frontend)

.NET 8 Web API (backend)

SQL Server (DB)

Hosting on IIS (Windows Server)

Continue reading...